题目很简单，描述如下：

把数字转化为 lcd 灯的表现形式，打印在控制台上。下面是 0~9 的样子：

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._.   ...   ._.   ._.   ...   ._.   ._.   ._.   ._.   ._.
|.|   ..|   ._|   ._|   |_|   |_.   |_.   ..|   |_|   |_|
|_|   ..|   |_.   ._|   ..|   ._|   |_|   ..|   |_|   ..|

例子: 910

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._. ... ._.
|_| ..| |.|
..| ..| |_|

测试用例如下：

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const main = require("../main/main");

describe("main()", () => {
  it("should return 910", () => {
    let actual = main("910");
    expect(actual).toBe("._. ... ._.\n" + "|_| ..| |.|\n" + "..| ..| |_|\n");
  });
  it("should return 256", () => {
    let actual = main("256");
    expect(actual).toBe("._. ._. ._.\n" + "._| |_. |_.\n" + "|_. ._| |_|\n");
  });

  it("should return 7", () => {
    let actual = main("7");
    expect(actual).toBe("._.\n" + "..|\n" + "..|\n");
  });
});

我的代码如下：

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function main(number) {
  let result = "",
    arr = [],
    line1 = "._.   ...   ._.   ._.   ...   ._.   ._.   ._.   ._.   ._.".split(
      "   "),
    line2 = "|.|   ..|   ._|   ._|   |_|   |_.   |_.   ..|   |_|   |_|".split(
      "   "),
    line3 = "|_|   ..|   |_.   ._|   ..|   ._|   |_|   ..|   |_|   ..|".split(
      "   ");
  arr.push(line1);
  arr.push(line2);
  arr.push(line3);

  for (let i = 0; i < 3; i++) {
    number.split("").forEach(element => {
      result += `${arr[i][element]} `;
    });
    result = result.slice(0, result.length - 1) + "\n";
  }
  return result;
};

看到洋神的优雅代码我真是惊了个呆，瞬间觉得自己写的代码好丑陋：

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function main(cs) {
  return cs
    .split("")
    .map(c => lcd[c])
    .reduce((x, y) => [x[0] + " " + y[0], x[1] + " " + y[1], x[2] + " " + y[2]])
    .map(l => l + "\n")
    .join("");
};

const lcd = {
  "0": ["._.", "|.|", "|_|"],
  "1": ["...", "..|", "..|"],
  "2": ["._.", "._|", "|_."],
  "3": ["._.", "._|", "._|"],
  "4": ["...", "|_|", "..|"],
  "5": ["._.", "|_.", "._|"],
  "6": ["._.", "|_.", "|_|"],
  "7": ["._.", "..|", "..|"],
  "8": ["._.", "|_|", "|_|"],
  "9": ["._.", "|_|", "..|"]
};